Good evening everybody! It was pretty darn blustery around the region today, and things will become even windier Saturday evening as one of the strongest storms since the tempestuous Hanukkah Eve Storm of 2006 roars through Western Washington.
So far, the biggest weather story today are the two tornadoes that hit Manzanita and Oceanside on the Oregon Coast. Tornadoes are extremely rare around here, and when we do see them, they are generally very weak and thin, rarely exceeding EF-0 or EF-1 status on the Enhanced Fujita Scale. For example, take a look at the waterspout off Cape Disappointment that formed on June 18th this past summer. Very pretty, but extremely weak.
Today’s tornadoes were much more robust than recent tornadoes we have seen. A sheriff in Manzanita said the tornado was “10 streets wide,” which would be a notable tornado even in the Great Plains. Here, it is not quite unheard of (Vancouver, WA saw an F-3 tornado in 1972 that killed 6 people and injured 301 others), but it is extremely rare. The mayor of Manzanita declared a “State of Emergency,” seeking assistance for the damage wrought by the tornado. Taking a peek at the damage below, it’s not hard to see why.
Most tornadoes here are “cold core” and are formed due to localized vortices within a thunderstorm rather than the thunderstorm rotating as a whole, which is how the massive tornadoes over the Great Plains are created. The storms that brought the tornadoes to the Oregon Coast did have rotation, and spun up two powerful tornadoes as a result. The tornado in Manzanita destroyed 128 homes and took town 1/3 of the town’s trees. Thankfully, nobody was injured.
Here’s a picture of the track of the Manzanita tornado, which was rated as an EF-2 by the NWS with max winds of 125-130 mph.
And here’s a video of the Manzanita tornado I found on Youtube. It’s a tad bigger than that waterspout back in June!
A look at the Langley Hill coastal radar around 8:20 am shows a ton of heavy showers off the coast, with a band of strong thunderstorms making landfall on the Southern Oregon coast. I’ve marked the location of the thunderstorm that brought the tornado to Manzanita with my mouse.
You can see it in better detail with the Portland radar. The cell is JUST north of Rockaway beach. The reds indicate very heavy rain, and the pink indicates where the heavens have opened up and is likely close to the tornado itself.
A look at the radiosonde (a package of weather sensors that take observations while rising through the atmosphere on a balloon) from Salem this morning shows a large decrease in temperature with height, which is necessary for strong thunderstorms.
I was unable to find much about the Oceanside tornado, but hopefully some more information will come out about that twister soon. I did find one amazing video online, shot by Saxon Williams.
When it comes to tornadoes, today was certainly one for the record books. The Portland NWS office summed it up best with their tweet this evening.
Another story was the extremely heavy rains that have impacted the Pacific Northwest. With strong, moist SW flow aloft, the windward slopes of the Olympics and North Cascades have been hit particularly hard, with Jefferson Creek on the Olympics picking up 7.05 inches of rain over the past 24 hours. When you consider that Jefferson Creek also got 4.19 inches in the previous 24 hours for a storm total of 11.24 inches over the past two days, it’s no surprise that the exceptionally flood-prone Skokomish River is currently experiencing minor flooding near Potlatch. If this storm had occurred later in the storm season when antecedent river levels were already high, we would see much more widespread flooding.
Even Seattle saw some urban flooding today courtesy of a band of heavy showers that moved through around 11 am. And Portland saw some urban flooding earlier this evening as a heavy squall ran roughly parallel to the city, dropping heavy rain on the area for an extended period of time.
And we have another round of heavy rain on the way with Saturday’s mega storm. But first, let’s talk about today’s winds.
Many places across the region saw some hefty gusts today. The Seattle NWS produced a nice graphical display of top gusts. Most of these occurred in the early afternoon, as the low pressure center passed to our north at generated a strong pressure gradient throughout Western Washington.
Gusts were even more impressive along the Oregon Coast. The Portland NWS neatly compiled a list of top gusts as well. Cape Meares, an exposed headland 2 miles east of Oceanside, has already broken the triple digit mark! These high winds were likely due to a very strong, low level “coastal jet,” with extremely strong winds several thousand feet above the surface that occasionally mixed down to produce intense gusts at the stations. Sustained winds at the 850 mb level of the atmosphere (around 5000 feet) were around 80 knots… extremely strong. And to think… the worst is yet to come.
Now, let’s talk about Saturday’s storm.
We can currently see Saturday’s storm on satellite near 135W, approximately 800 miles of the Californian Coast. We are just starting to see a little “notch” on the western side of the storm. This is known as a “dry slot,” and is the calling card of a rapidly developing cyclone.
Models are currently in agreement that this storm will rapidly develop and curve to the NE, crashing aboard the Olympic Peninsula or Southern Vancouver Island as an extremely compact 970 mb low. Because the storm is so compact, very slight changes in track will result in huge differences in wind speed, particularly for the Puget Sound region. This is because Puget Sound is often sheltered high winds by the Olympics when storms pass far offshore, but if storms are much closer, extremely tight pressure gradients – and very strong winds – can occur directly over the Puget Sound lowlands.
Here’s a quick comparison of storm tracks that the different models are showing. This was created by the Seattle NWS forecast office. You have to tip your hats off to those folks; they’ve been working nonstop not only forecasting this storm but talking to the community and media as well.
If you compare this to a similar graphic, you can see that the models have agreed on a “compromise solution,” with the GFS moving further south and the European coming further north. Interestingly, the NAM, which is generally much less accurate than the GFS, has been the most consistent performer. I have always called the NAM the “Never Accurate Model,” but I’ve gained some respect for it over the past couple days.
For us, a track like the GFS is showing would be a worst-case scenario for Western Washington. However, the GFS model is significantly weaker than the other models. Meanwhile, a track like the Canadian is showing would give us “very windy” conditions, but it wouldn’t be a storm you’d tell your grandkids about.
The difference in tracks is likely due to how quickly the models develop the storm. When storms explosively develop, they tend to curve northward. The stronger and quicker the development, the further north the storm goes. Let’s take a look at how the latest WRF-GFS model from the UW develops this storm.
At 8 AM Saturday, the storm is a rapidly deepening 980 mb cyclone off Central Oregon.
By 11 am, the storm has deepened and raced to the NE.
At 2 pm, the storm hooks to the NNE and continues to deepen. It is currently a 972 mb cyclone at this time.
Deepening further to 970 mb, the low bolts up the coast. The central coast is experiencing incredibly strong winds at this time, and Puget Sound is blustery.
At 8 pm, the low crosses the Olympic Peninsula and weakens slightly as the Olympics disrupt the intensification. Puget Sound gets major wind, especially north of Seattle.
By 11 pm, the storm is just a touch north of Squamish, BC and winds are dying down across the region.
One thing to note is just how quickly this storm is moving. As modeled, it covered a distance of about 500 miles in 15 hours. 500/15 = 33 miles per hour. That’s fast. Fast-moving storms cause stronger winds because they are indicative of stronger winds aloft that can mix down to the surface and cause extremely rapid changes in pressure gradients at the surface. Additionally, when storms are moving quickly, they are also often undergoing “bombogenesis,” or strengthening extremely quickly. When a cyclone is strengthening, it has a more intense gradient near the center of the storm. The more intense the gradient, the stronger the winds. So, those are two things this storm has “going for it” in terms of giving high winds to the area.
On the other hand, the pressures ahead of this storm are already quite low due to the storm that just swung through, meaning that there pressure gradients will be lower than they otherwise would be, particularly further away from the storm. Lower pressure gradients = lower winds. Additionally, this low is so compact that even with it tracking across the Olympic Peninsula, the highest winds don’t quite stretch far enough east to Seattle.
Models can often underestimate the depth of a extratropical cyclone, and it’s not unheard of for cyclones to be 8 mb deeper at landfall than shown by the models. Additionally, other models, like the European model, are a good 5 mb deeper than the GFS. I would not be surprised if the low deepened below 970 mb.
Considering those factors and what I’m seeing on satellite right now, I’m expecting that the low will be slightly further north, perhaps making landfall around Tatoosh Island, and be more intense than forecast, around 965 mb. This track would bring devastating winds to places like Hoquiam and would give damaging, but not historic, winds to the Puget Sound area.
Here’s what I’m expecting for winds. I will refine this forecast as new models come in and we watch the storm develop on satellite.
Coast: Highest winds around 10 am for the southern Oregon Coast and 6 pm for the northern Washington Coast. Sustained winds of 40-50 with gusts to 70 in many locations, with highest winds near Hoquiam/Long beach up to La Push. Exposed headlands like Cape Blanco, Sea Lion Caves, Cape Meares, and Mt. Hebo in Oregon and Naselle Ridge and Destruction Island in Washington could easily see gusts surpassing 100 mph. Also, expect very high seas with waves up to 25 feet, creating the potential for coastal flooding. Though this is less than feared earlier, 25 foot waves are nothing to sneeze at.
Willamette Valley: Sustained winds 20-30 mph, with gusts to 50, strongest from 1-5 pm.
SW WA: Sustained winds 20-35 mph, with gusts to 55. Strongest from 2-6 pm.
Puget Sound: Sustained winds 25-35 mph, with gusts to 60. Strongest from 5-8 pm.
Northern Interior: Sustained winds 30-40 mph, with gusts to 70. Strongest winds 6-9 pm.
Although winds will be the primary impact, this storm will bring a ton of precipitation to the area. Expect around an inch in Puget Sound, up to two inches in the Willamette Valley, and a TON of precipitation in the coastal mountains of Southern Oregon – perhaps as much as 10 inches in spots.
Credit: University of Washington Atmospheric Sciences
I’ll leave you with one more image – a simulated infrared satellite picture by the UW WRF-GFS. You don’t need to be a meteorologist to see that that is a beast of a storm.
Credit: University of Washington Atmospheric Sciences
The bottom line is that people in the Puget Sound area should prepare for the most significant storm since the Hanukkah Eve Storm of 2006. Though I’m not forecasting this storm to meet or exceed that storm at this point, it could very well exceed the Hanukkah Eve Storm if the low deepens more than expected and makes landfall across the Olympic Peninsula. Models were showing a historic storm in Portland just a couple days ago, but it now appears that Portland will be spared from the brunt of the storm.
And last, but CERTAINLY not least…
KEEP AWAY FROM TREES AND POWER LINES DURING STRONG WINDS, AND NEVER EVER RUN A GENERATOR INDOORS. Review my previous post on storm safety for more tips to keep yourself safe before, during, and after the storm.
Enjoy the wind, but stay safe.
Charlie
